<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <title></title>
    <style>
    .father {
      width: 400px;
      height: 400px;
      background-color: red;
      display: flex;
      justify-content: center;
      align-items: center;
    }
    .son {
      width: 200px;
      height: 200px;
      background-color: orange;
    }
    </style>
    <link href="css/style.css" rel="stylesheet">
  </head>
  <body>
    <div class="father">
      <div class="son"></div>
    </div>
  
  </body>
</html>
